Development and Photonic Integration of Efficient and Stable Silicon-Based LED

为了开发高效稳定的硅基发光二极管，为单片光子集成奠定坚实的技术基础，本文从制作工艺、表面钝化及相关光电特性等方面进行了实验研究。主要研究结果及其意义如下：1.硅基LED效率的大幅提高通过引入阳极化后的电化学处理，多孔硅二极管电流中的泄漏分量成功降低，并且载流子注入到发光纳米晶硅中变得非常有效。结果，外量子效率提高到1%以上。此外，外部功率效率为0.4%，接近实际水平，可以从二极管与适当的设备配置。这是该领域迄今为止的最高值。还澄清了LED操作的稳定性和调谐发射带的一些关键问题。特别重要的结果是，在不含氧化物的样品中观察到了蓝光发射.硅纳米晶新功能的发现从一些电学和光学研究中，已经表明发光纳米晶硅具有各种有用的功能：光发射非易失性存储器，弹道电子发射和热致超声发射。纳米硅是一种非常有用的多功能材料.研究了纳米晶硅与三维埋层光波导的兼容性。已经证明，具有极小曲率的掩埋弯曲波导可以通过简单的palanar加工来制造。还观察到由于折射率变化引起的非线性光学效应。

To develop efficient and stable silicon-based LED and make the technological foundation of monolithic photonic integration more solid, experimental studies have been conducted in terms of fabrication technique, surface passivation, and related optoelectronic characterization. The major results and their significances are summarized as follows.1. Drastic improvement in the efficiency of Si-based LEDsBy introducing a post-anodization electrochemical treatment, the leakage component in the porous silicon diode current is successfully reduced, and carrier injection into luminescent nanocrystalline silicon becomes very efficient. As a result, the external quantum efficiency is enhanced to beyond 1%. Also, an external power efficiency of 0.4% close to a practical level can be obtained from a diode with an appropriate device configuration. These are the highest values to date in this field. Some key issues for stabilization of LED operation and for tuning the emission band have also been clarified. Especially important result is that blue emission has been observed with oxide-free samples.2. Findings of novel functions of silicon nanocrystalsFrom some electrical and optical investigations, it has been shown that luminescent nanocrystalline silicon exhibits various useful functions : light-emissive nonvolatile memory, ballistic electron emission, and thermally induced ultrasonic emission. Nanocrystalline silicon is very useful as a multi-functional material.3. Toward photonic integrationThe compatibility of nanocrystalline silicon with three-dimensional buried optical waveguide was examined. It has been demonstrated that a buried bent waveguide with an extremely small curvature can be fabricated by simple palanar processing. Nonlinear optical effects due to refractive index change were also observed.